Field of the of the Present Disclosure
The disclosure relates to a miniaturized scanning system to generate 2D movement of a distal part of a medical tool.
Background Art
The Applicant has developed a confocal imaging system based on a fiber bundle probe for in vivo in situ imaging of biological tissues as described for example in US Patent Application 2005/0242298 which is fully incorporated herein by reference. Such a system, also referred as a fibered confocal microscope, is for example represented schematically on FIG. 11. A laser 140 is scanned over a proximal face 112 of a fiber bundle probe 110 which is connected to a light injection module 130 via an abutment 120. The light injection module 130 comprises an objective ensuring that light from the laser is properly injected into each fiber of the fiber bundle probe. Scanning the proximal face of the fiber bundle results in a fiber per fiber injection of light and, at a distal end of the bundle 111, in a point per point illumination of an object under observation. As a consequence, each illuminated point of the observed object may re-emit light which is collected using an optical head and transported back to the proximal end 112 of the fiber bundle via the same fiber and finally transmitted to a detector through the same scanning process.
The single images acquired by fibered confocal microscopy typically cover an area of 240×200 μm2. The smallness of the image size is due on the one hand to the necessity of a high level of resolution and, on the other hand, because the optical lenses housed in the optical head and the fiber bundle probe carrying the images are minimized for minimal invasiveness. A single image is not always large enough for a conclusive diagnostics and solutions have been developed to obtain high resolution images with a large field of view based on scanning the tissue area by moving the optical head of the imaging system and merging the collected images. US Patent Application 2009/0041314 in the name of the applicant describes image mosaicing techniques that can be used to provide efficient and complete representation of an enlarged field of view. With a mosaicing algorithm as described in US 2009/0041314, a sample scan of 3 mm2 on tissue typically requires maintaining a distance of 150 μm from a previously traced line with an approximate precision of 25 μm for a continuous duration of approximately one minute. With manual sweeping, it is difficult to obtain this precision for such a long time. Further, manual sweeping may not provide the smoothness of the motion with minimal accelerations and/or changes of directions which are important when the surface to be scanned over is a biological tissue.
Several assisted handheld instruments are presented in the literature (see for example B. C. Becker, R. A. MacLachlan, L. A. J. Lobes, and C. N. Riviere, “Semiautomated intraocular laser surgery using handheld instruments”, Lasers in Surgery and Medicine, vol. 42, pp. 246-273, 2010).
US 2001/0055462 from Siebel et al. describes an endoscopic image acquisition system, in which a unique optical fiber is driven across the field of view using two pairs of piezoelectric actuators, placed along the optical fiber at a distal end of the imaging system and oscillating in quadrature, thereby forcing the fiber to bend with the tip of the fiber describing a spiral. The fiber movement is driven close to the resonance frequency of the piezoelectric actuators so that large bending amplitudes can be reached. However, high resonance frequency is required to image a tissue in real time and this technique can hardly be used with heavy movable element.
The Applicant proposes herein under a miniaturized scanning system that can generate a 2D movement of a distal part of a medical tool, for example a surgical or endoscopic tool, while preserving the scanning accuracy, its reproducibility and the smoothness of the movement, and may be applied to any medical tool in which the distal part comprises a bulky movable element, e.g. a fiber bundle associated with a distal optical head, a catheter, a therapeutic device or the like.